What’s in there? Scientists fascinated after Nasa orbiter photographs open crater leading into underground cavern on Mars

The hole was discovered by chance on images of the dusty slopes of the Red Planet’s Pavonis Mons volcano. It appears to be an opening to an underground cavern, partly illuminated to the right of the opening. Analysis of this and follow-up images revealed the opening to be about 35 meters across. The interior shadow angle indicates that the underlying cavern is roughly 20 meters deep.